Can you open your phone and run an app with voice commands?

[SteveJG]

Here is a google search of App Inventor and Alexa.

Here is a search of the community Search results for 'alexa' - MIT App Inventor Community

Perhaps some of interest is there ?

Use the SpeechRecognizer to command activities, go to a url etc. while the app is active using Blocks:

HOW TO: Program the native SpeechRecognizer for Continuous Dictation and to do things

[parrot] HOW TO: Program the native SpeechRecognizer for continuous dictation and to do things is an example app that shows how to make the native SpeechRecognizer work. It is not a step by step tutorial. The SpeechRecognizer tutorial example is Speech Recognizer Parrot. Use voice commands to do different things; command something to happen, use it as a typewriter. amaze your children etc. Parrot can provide continuous recognition (more or less) or not depending on how you use it and how you…

@MitAppInventorFan

wonder if it responds to voice even if the phone is closed.

I am not aware of anything that will respond if your phone is turned off or sleeping. Chris' suggestion might work.